Skandapurana 5.8.108

5.8.108

eṣa yajñopavītāḍhyo viśeṣāttapasi sthitaḥ.
chalena nihataḥ śakra tena tvaṃ pāpasaṃyutaḥ .. 108 .. ..

This one was endowed with a sacred thread, especially engaged in austerity;
he was slain by trickery, O Śakra; therefore you are joined with sin. 108